var RecentCounter = function() {
  this.q = [];
};

/** 
* @param {number} t
* @return {number}
*/
RecentCounter.prototype.ping = function(t) {
  this.q.push(t);
  while (this.q[0] < t - 3000) {
      this.q.shift();
  }
  return this.q.length;
};

/**
* Your RecentCounter object will be instantiated and called as such:
* var obj = new RecentCounter()
* var param_1 = obj.ping(t)
*/